Refer to FIG. 1. FIG. 1 is a three-dimensional diagram of a conventional light-emitting diode illumination device. A light-emitting diode illumination device 100 comprises a light fixture 102 and a typical light-emitting diode light bulb 112. The light-emitting diode light bulb 112 includes a driver portion 104, a base 106, a light-emitting diode light plate 108 and a lamp cover 110. The light-emitting diode light plate 108 is disposed on the base 106, the base 106 along with the light-emitting diode light plate 108 set thereon are disposed on the driver portion 104, and the lamp cover 110 covers the light-emitting diode light plate 108. The light-emitting diode light plate 108 includes a circuit board 116 and a plurality of light-emitting diodes 114, wherein the light-emitting diodes 114 are disposed on the circuit board 116 and are electrically connected to the driver portion 104. By disposing the driver portion 104 of the light-emitting diode light bulb 112 on the light fixture 102, the light-emitting diode light bulb 112 can be assembled in the light fixture 102 to complete the fabrication of the light-emitting diode illumination device 100.
The light fixture 102 is a direct type light fixture, i.e. the illumination direction is from top to bottom. Therefore, when the light-emitting diode light bulb 112 is assembled in the direct type light fixture 102, light of the light-emitting diode light bulb 112 is emitted from top to bottom as the illumination direction of a direct type light fixture, so that the illumination of the light-emitting diode illumination device 100 is not affected.
Refer to FIG. 2. FIG. 2 is a three-dimensional diagram of another conventional light-emitting diode illumination device. A light-emitting diode illumination device 100a comprises a light fixture 102a and the light-emitting diode light bulb 112. In the conventional light-emitting diode illumination device 100a, the light-emitting diode light bulb 112 is used to replace a fluorescent bulb in another conventional fluorescent light fixture. The light-emitting diode illumination devices 100a and 100 use the same light-emitting diode light bulb 112. The difference between the light-emitting diode illumination devices 100 and 100a is that the light fixture 102a is a lateral type light fixture, i.e. a connection socket 118 of the light fixture 102a extends laterally from an inner side surface of the light fixture 102a. The light fixtures shown in FIGS. 1 and 2 are recessed lamps, for example.
When the light-emitting diode light bulb 112 is assembled, the driver portion 104 of the light-emitting diode light bulb 112 is installed into the connection socket 118 on the inner side surface of the light fixture 102a. At present, the light-emitting diode light bulb 112 is laterally disposed in the light fixture 102a, and the light-emitting diodes 114 (refer to FIG. 1) on a front end of the light-emitting diode light bulb 112 face the inner side surface of the light fixture 102a. The illumination direction of the light-emitting diodes 114 has directivity, so that the light emitted by the light-emitting diodes 114 projects onto the inner side surface of the light fixture 102a. Accordingly, the light emitted by the light-emitting diode light bulb 112 cannot be fully reflected downward, thereby greatly reducing the illumination of the light-emitting diode illumination device 100a. 
Therefore, in the current light-emitting diode light bulb, the illumination direction of the light-emitting diodes has directivity, so that the light-emitting diode light bulb only can be applied in a direct type light fixture and cannot be applied in a lateral type light fixture.